The present invention relates to an antenna for an integrated circuit card and to an integrated circuit card including such an antenna. Cards of this type can be connected to a reader over a contactless link by radio or magnetic coupling.
In a well known embodiment, a card of this type comprises a card body of insulating material having embedded therein an antenna with ends constituted by conductive layers forming connection terminals, and an integrated circuit module received in a cavity of the card body and provided with internal connection areas connected to the connection terminals of the antenna.
The antenna is generally embedded in the body of the card during a laminating operation, i.e. the antenna is disposed between two layers of the card body which are heated and pressed one against the other.
It has been found that the insulating material constituting the body of the card has difficulty in adhering to the copper constituting the connection terminals. This gives rise to poor cohesion of the card body in the vicinity of the connection terminals of the antenna, thereby limiting the strength of the card. This poor cohesion is particularly unfortunate when the connection terminals are large in area. Nevertheless, it is undesirable to reduce this area since a relatively large area makes it easier to position the integrated circuit module relative to the connection terminals of the antenna.
To resolve that problem, proposals have therefore been made to cover the connection terminals in adhesive. The improvement in card body cohesion provided by adhesive is nevertheless insufficient to confer the desired strength to the card.
An object of the invention is to provide means for ensuring good cohesion of the card body in the vicinity of the antenna connection terminals without reducing the area thereof.
To achieve this object, the invention provides an antenna for an integrated circuit card, the antenna comprising a conductive track forming at least one turn and having ends comprising conductive layers forming connection terminals, the antenna being characterized in that the connection terminals and/or the conductive track are perforated.
Thus, when the antenna and the card body are laminated, card body material on either side of the connection terminals flows through the perforations in the connection terminals and/or the conductive track and welds to itself through the perforations. Cohesion of the card body in the vicinity of the connection terminals and/or the conductive track of the antenna is then high and the strength of the card is improved.
In a particular embodiment, the connection terminals present slots in the form of strips. This strip form serves to obtain a large flow section for the material constituting the card body through the perforations in the connection terminals of the antenna, while nevertheless preserving sufficient conductive area to ensure good electrical connection with the integrated circuit module of the card.
The slots are preferably of undulating outline.
The risk of a connection terminal and/or the conductive track of the antenna breaking when a force is applied to the card is thus minimized regardless of the direction of the force.
The invention also provides an integrated circuit card including an antenna having at least one of the above-specified characteristics.
Other characteristics and advantages of the invention will appear on reading the following description of a particular, non-limiting embodiment of the invention.